Contents
2010
Volume: 30 Issue 12
52 Article(s)
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Research Article
Atmospheric Optics and Oceanic Optics
High-Order Singular Value Decomposition Applied in Aero-Optical Effects Analysis
Xu Dong, Liu Haowei, Wu Lin, and An Yongquan
Third-order tensor is introduced to represent 3D density field of turbulence. The third-order tensor is decomposed with high-order singular-value decomposition (HOSVD) method to get singular values and corresponding eigenvector. Several great singular values and corresponding eigenvectors are used to reconstruct the deThird-order tensor is introduced to represent 3D density field of turbulence. The third-order tensor is decomposed with high-order singular-value decomposition (HOSVD) method to get singular values and corresponding eigenvector. Several great singular values and corresponding eigenvectors are used to reconstruct the density field which is the optimal approximation of the original flow field and gives the large-scale coherent structure in 3D turbulence. The reconstructed 3D density field involves the dominated information of the original flow field. The simulation results of aero-optical effect give the evidences that light transmission in reconstructed field is similar to original field..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3367 (2010)
Study of Extinction Characteristics of Solar Radiation by Soot Aerosols
Lei Chengxin, Zhang Huafu, and Liu Hanfa
Based on fractal theory, the cluster-cluster aggregation (CCA) model is used to simulate the fractal structure of the soot aerosols in random orientation using Monte-Carlo method, and the absorption, scattering and extinction efficiency factors of fractal soot aerosols in random orientation are simulated in the solar rBased on fractal theory, the cluster-cluster aggregation (CCA) model is used to simulate the fractal structure of the soot aerosols in random orientation using Monte-Carlo method, and the absorption, scattering and extinction efficiency factors of fractal soot aerosols in random orientation are simulated in the solar radiation spectrum ranging from 0.2 to 10.0 μm of wavelength by the discrete dipole approximation (DDA) method. The influential rules about the solar radiative wavelength, diameter and the number of primary particles on the extinction characteristics of soot aerosols in random orientation are provided. The comparison of the numerical results obtained by the DDA method with T matrix method shows that the results by two methods are very similar which verifies the validity of DDA method. It is shown that the carbon and fly ash aerosols have different influences of extinction characteristics on solar radiation, whose radiative wavelength ranges from ultraviolet to near infrared bands, and the extinction characteristics of solar radiation by soot aerosols are mainly determined by the radius and the number of primitive particles besides the refractive index..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3373 (2010)
Diffraction and Gratings
Influence of Grating Boundary Shapes on Diffraction Properties of Gaussian Pulsed Beam
Hu Zhijuan, Dai Cuixia, and Du Guoping
Based on the three-dimensional coupled wave theory and the two-dimensional Runge-Kutta methods, diffraction properties of ultrashort pulsed Gaussian beams by volume holographic gratings (VHG) with truncated boundaries are studied. Effects of the polarizations of the readout beams and the grating boundaries on the intenBased on the three-dimensional coupled wave theory and the two-dimensional Runge-Kutta methods, diffraction properties of ultrashort pulsed Gaussian beams by volume holographic gratings (VHG) with truncated boundaries are studied. Effects of the polarizations of the readout beams and the grating boundaries on the intensity distributions of diffracted pulsed beams in spectral and temporal domains are presented, and the effects on Bragg selectivity bandwidth, the total diffraction efficiency of gratings are also given. Simulation results show that the Bragg selectivity bandwidth and the distributions of the diffracted pulsed beams along the output boundary of local holographic gratings in spectral and temporal domains can be improved, and the diffracted pulsed beams with better beam quality and higher diffraction efficiency can be obtained by choosing the truncated parameters of local holographic gratings, controlling the polarizations of the readout beams and choosing the pulse duration of readout pulsed beams..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3378 (2010)
Fiber Optics and Optical Communications
Frequency Quadrupling for Single-Sideband Optical Millimeter-Wave Up Conversion
Xu Gang, Zheng Xiaoping, and Zhang Hanyi
A novel scheme is demonstrated to generate single-sideband optical millimeter-wave signals employing frequency quadrupling. A dual parallel Mach-Zehnder modulator (DPMZM) is used to achieve frequency quadrupling. With electrical phase shifting and bias control, the DPMZM generates optical signal comprised of a carrier A novel scheme is demonstrated to generate single-sideband optical millimeter-wave signals employing frequency quadrupling. A dual parallel Mach-Zehnder modulator (DPMZM) is used to achieve frequency quadrupling. With electrical phase shifting and bias control, the DPMZM generates optical signal comprised of a carrier and two two-order side-bands. After removing the optical carrier with an optical filter, a quadruple optical millimeter-wave signal is generated. An experimental radio-over-fiber (RoF) transmission system is built. 40 GHz optical millimeter-wave signal with 1 Gb/s pseudorandom bit sequence data is transsmited, whose power penalty is only 0.8 dB over 20 km single-mode fiber (SMF)..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3386 (2010)
Twin-Core Fiber-Based Long-Period Fiber Grating and Its Coupling Characteristics
Wang Xue, Lu Mifang, Yang Jun, and Yuan Libo
A twin-core fiber-based long period fiber grating has been proposed. It makes two long-period gratings in parallel and integrates the two components in one fiber. The mode coupling between two same pattern long-period fiber gratings in this twin-core fiber is also investigated. Simulation results show that different trA twin-core fiber-based long period fiber grating has been proposed. It makes two long-period gratings in parallel and integrates the two components in one fiber. The mode coupling between two same pattern long-period fiber gratings in this twin-core fiber is also investigated. Simulation results show that different transmission spectrum with three different exposure directions on circular cross section of the fiber can be obtained. The twin-core long-period fiber grating is fabricated by using CO2 laser pulse exposure approach. The best way to achieve this twin-core long period fiber grating is also given by experiment.It is shown that the transmission spectrum characteristics of the two long-period gratings written in the twin-core fiber depend on the CO2 laser pulses exposure direction on the fiber circumference..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3391 (2010)
Research on Characteristic of Fiber Optic Hydrogen Sensor Based on Palladium and Its Composite Films
Liu Hongliang, Yang Minghong, Dai Jixiang, Li Xiaobing, Liao Zhaolong, and He Wei
A novel fiber-optic hydrogen gas sensor is proposed. The side of fiber cladding is polished to "D" shape, Pd and Pd/WO3 hydrogen-sensitive films are coated on the polished surface by magnetron sputtering, then an evanescent field fiber-optic hydrogen sensor is fabricated. The results show that a sensor which A novel fiber-optic hydrogen gas sensor is proposed. The side of fiber cladding is polished to "D" shape, Pd and Pd/WO3 hydrogen-sensitive films are coated on the polished surface by magnetron sputtering, then an evanescent field fiber-optic hydrogen sensor is fabricated. The results show that a sensor which has composite Pd/WO3 thin film has good linerarity and repeatability. Meanwhile, compared with multi-mode fiber, single-mode fiber is more reliable..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3398 (2010)
An Effective Way of Reducing Coupling Loss between Rectangular Laser and Conventional Fiber
Sun Guilin, 2Chen Zilun, Xi Xiaoming, Hou Jing, and Jiang Zongfu
An anamorphic photonic crystal fiber (PCF) is introduced to improve the coupling loss between rectangular laser and conventional single-mode fiber. One end with rectangular core is connected with laser, the other end with round core connect with conventional fiber. Firstly, the coupling efficiency is calculated by beamAn anamorphic photonic crystal fiber (PCF) is introduced to improve the coupling loss between rectangular laser and conventional single-mode fiber. One end with rectangular core is connected with laser, the other end with round core connect with conventional fiber. Firstly, the coupling efficiency is calculated by beam propagation method. Then after blocking four holes of the PCF, and inflating, heating, an anamorphic core-shape PCF is formed with four holes absolutely collapsed. The simulation results show that, comparing to the straight coupling between rectangular laser and conventional single-mode fiber, more than 3.9 dB improvement of coupling efficiency is achieved by this new method. And the experimental results show that the new structure is feasible..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3403 (2010)
Probability Density of Phase Noise in Optical Phase-Modulated Transmission Systems
Xi Lixia, WangShaokang, and Zhang Xiaoguang
Phase noise is considered as one of the main sources of signal impairments in optical phase-shift-keying (PSK) systems. The main sources of linear phase noise and nonlinear phase noise are introduced. The linear phase noises arise from amplified spontaneous emission (ASE) of each in-line amplifier and the nonlinear phaPhase noise is considered as one of the main sources of signal impairments in optical phase-shift-keying (PSK) systems. The main sources of linear phase noise and nonlinear phase noise are introduced. The linear phase noises arise from amplified spontaneous emission (ASE) of each in-line amplifier and the nonlinear phase noises are induced by the fiber Kerr effect. The probability density functions (PDF) of linear phase noise and nonlinear phase noise are obtained respectively by theoretical analysis. The probability distribution of linear phase noise, nonlinear phase noise and total phase noise in fiber links are also obtained by statistical simulation, and are compared with Gaussian distribution. The results show that the Gaussian model can reflect noise distribution in practical fiber links when input signal power is low, while failed to accurately characterize systems when the nonlinear contribution to phase noise becomes dominant..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3408 (2010)
Free Space Optical 2×4 90° Hybrid Based on Crystal Birefringence
Hou Peipei, Zhou Yu, Zhi Yanan, Sun Jianfeng, and Liu Liren
The design and fabrication of an optical 2×4 90° hybrid based on crystal birefringence for coherent receiver in free-space optical communication system are presented. The two pairs of balanced optical signals combined by the signal beam and local oscillator beam are output, which obtains the accurate phase diThe design and fabrication of an optical 2×4 90° hybrid based on crystal birefringence for coherent receiver in free-space optical communication system are presented. The two pairs of balanced optical signals combined by the signal beam and local oscillator beam are output, which obtains the accurate phase difference of 90°, realizes 2×4 free-space hybrid, carries out photoelectric conversion and signal demodulation phase-lock. The 90° hybrid comprises two pairs of stacked birefringent plates, an analyser birefringent plate and a phase retardation plate. The testing results measured by heterodyne method verify that the 2×4 optical 90° hybrid can run accurately, effectively, stably and reliably. The phase compensation and further optimization schemes are also proposed. The free-space optical hybrid based on birefringence is particularly suitable for free-space coherent optical communication system, for intersatellite communications terminal for future compact, lightweight, low power consumption and high bit rate in the future..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3413 (2010)
48 Optical Millimeter Waves Generated by Phase Modulation within an Active Fiber Ring Resonator
Hu Zongfu, and Chen Yu
Design and characteristics of a light source of multiple optical millimeter waves, based on optical phase modulation within an active fiber ring resonator, is theoretically studied. With balanced and optimal design of phase modulation index, the coupling coefficient of input-output coupler, the net loss of the resonatoDesign and characteristics of a light source of multiple optical millimeter waves, based on optical phase modulation within an active fiber ring resonator, is theoretically studied. With balanced and optimal design of phase modulation index, the coupling coefficient of input-output coupler, the net loss of the resonator, and the bandwidth of the bandpass filter, 48 40 GHz optical millimeter waves with acceptable amplitude uniformity can be obtained. Effect of initial phase noise of optical millimeter waves on its frequency bandwidth is analyzed. The frequency bandwidth may be less than 100 Hz if the linewidth of input laser and the resonator length are less than 100 KHz and 4 m, respectively. The relation between the waves′ amplitude variation and fluctuation of the index, optical amplifier gain, and the resonator length are given..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3419 (2010)
Fabricating and Testing of High-Accuracy Optical-Fiber Dimension Transform Element
Liang Jingqiu
In order to improve the accuracy of the optical-fiber dimension transform element (OFDTE) which is used in spatial exploration, imaging system, iatrology and military reconnaissance, the plane arranging method of fiber array based on silicon V-grooves is established. Firstly, the system error of the OFDTE is analyzed. In order to improve the accuracy of the optical-fiber dimension transform element (OFDTE) which is used in spatial exploration, imaging system, iatrology and military reconnaissance, the plane arranging method of fiber array based on silicon V-grooves is established. Firstly, the system error of the OFDTE is analyzed. Then, experiments are performed on arranging fibers, solidifying glue, polishing end surface and packaging device. Finally, a 1×2 OFDTE containing 2000 optical fibers is fabricated. The measurement results indicate that the maximum error accumulated in 2000 periods of the silicon V-grooves is 0.5 μm, and the error of the height in Si-V grooves is less than 0.15 μm. The value of root mean square of roughness of the end face is less than 0.9 nm. Furthermore, the position error of the end surface in 2000 periods is 190.5 nm. The transmittance of the OFDTE without optical film is 51.46% at the wavelength of 632.8 nm. After random vibration experiment, the ratio of the broken fiber increases by 0.1%. The characteristics of device keep stable when environmental temperature is changed within -40 ℃ to 40 ℃..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3425 (2010)
High-Speed Digital Beam Scanner Based on Electro-Optic Crystal Switch Array
Zhi Yanan, Yan Aimin, Shu Rong, Sun Jianfeng, Zhou Yu, and Liu Liren
A high-speed digital beam scanner based on electro-optic crystal switch array is developed. The scanner is composed of electro-optic beam splitter unit and deflection prism array. The electro-optic beam splitter unit is combined by LiNbO3 electro-optic switch and polarized beam splitter. The 3×3 rectangle beam scaA high-speed digital beam scanner based on electro-optic crystal switch array is developed. The scanner is composed of electro-optic beam splitter unit and deflection prism array. The electro-optic beam splitter unit is combined by LiNbO3 electro-optic switch and polarized beam splitter. The 3×3 rectangle beam scanning array is achieved by multistage cascade and space composition of electro-optic beam splitter units. The prism array behind beam scanning array can provide required angle deflection. The large-range far-field beam array scanning can be achieved. The beam scanning and tracking can be real-time controlled by programming. The systematical experiments confirm that the designed parameter of beam scanner agrees with the measured results..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3430 (2010)
Image Processing
Auto-Focus Method Based on Autocorrelation of Derivative Image
Huang Yan, Xu Qiaoyu, Ye Dong, and Che Rensheng
Fast auto-focusing technology is a crucial technology in computer vision and digital video system. A novel rapid auto-focusing method is proposed according to the model of optical defocusing system by using autocorrelation of derivative image. Firstly, a Laplacian operator is used to search an isotropic second-order diFast auto-focusing technology is a crucial technology in computer vision and digital video system. A novel rapid auto-focusing method is proposed according to the model of optical defocusing system by using autocorrelation of derivative image. Firstly, a Laplacian operator is used to search an isotropic second-order differential to the defocused image and get the autocorrelation of the derivative image. Then, the radius of point spread function, that equals the blur′s radius of the defocused image, can be obtained from the annular groove of the autocorrelation. Finally, the right focus position can be deduced from the geometric relation between the radius of blurred spot and the defocusing value. The experimental results show that this proposed method can accurately estimate the radius of blurred spot and the right focus position for any target. Compared with the traditional methods based on focus criteria functions, this method only needs 2 defocused images that reduce the computation quantity and simplify the system to meet the fast auto focusing requirement..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3435 (2010)
Object Reconstruction of Fourier-Telescopy Based on All-Phase Spectrum Analysis
Chen Wei, Li Quan, and Wang Yangui
Fourier telescopy (FT) is an active imaging technology which interferes several spatial diverse, frequency-encoded laser beams on a distant target, and reconstructs the object image by demodulating the reflected time signals of intensity. A new approach of processing the time history of the reflected intensity for objeFourier telescopy (FT) is an active imaging technology which interferes several spatial diverse, frequency-encoded laser beams on a distant target, and reconstructs the object image by demodulating the reflected time signals of intensity. A new approach of processing the time history of the reflected intensity for object reconstruction of FT is devised based on all-phase spectrum analysis. The phase and amplitude of the FT signals could be educed by all-phase fast Fourier tansform (apFFT) directly and exactly. Then, after eliminating unknown atmospheric phase errors by phase-closure algorithm, the object image could be reconstructed. Compared with the traditional approach, this method can avoid frequency errors of the reflected signals from objects, because the measurement of the phase and amplitude need not depend on the signal frequency. So, it is of great advantage to applying FT to fast moving targets, such as low earth objects (LEO), because the speed errors of the targets will lead to the frequency errors of the reflected signal, which will degrade the reconstruction. Another advantage of this method is that it can eliminate the piston jitter of atmospheric aberrations and the spectrum-shift errors of acoustic-optic modulators to a certain extent, which also leads to the frequency errors of signals. The feasibility of this method is verified by computer simulation. Compared with the traditional method in two situations: the signal with noise and with frequency errors, the new method has the great ability to eliminate the frequency error while not degrading its repression of noise..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3441 (2010)
Experimental Research of Evaluating Methods of Image Quality Based on Models of S-CIELAB and iCAM
Wu Haili, Huang Qingmei, Yuan Xinfang, and Li Ruiling
S-CIELAB model and iCAM model are used for estimating the image quality by calculating the color difference between the original image and the distorted image. When the models is used to evaluate the image difference, the S-CIELAB model compensates for the effect of spatial scale of the human visual system. iCAM model,S-CIELAB model and iCAM model are used for estimating the image quality by calculating the color difference between the original image and the distorted image. When the models is used to evaluate the image difference, the S-CIELAB model compensates for the effect of spatial scale of the human visual system. iCAM model, in addition to considering the spatial scale dependency, takes into account the effect of chromatic adaptation on colour appearance. The effectiveness and accuracy of these two kinds of models are investigated based on visual perception experiments using three images with sharp colour contrasts. The study shows that the predictions of iCAM model are more consistent with human visual performance than those of S-CIELAB model..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3447 (2010)
New Analytical Line Spread Function Fitting Model for Modulation Transfer Function Calculation
Li Tiecheng, Feng Huajun, Xu Zhihai, and Li Xiaotong
The modulation transfer function (MTF) has been widely used to characterize and quantify the spatial resolution of a linear and space-invariant imaging system. Various methods have been proposed to determine the MTF of an imaging system. A new analytical line spread function (LSF) fitting model to calculate the MTF is The modulation transfer function (MTF) has been widely used to characterize and quantify the spatial resolution of a linear and space-invariant imaging system. Various methods have been proposed to determine the MTF of an imaging system. A new analytical line spread function (LSF) fitting model to calculate the MTF is proposed. The LSF parameters are confirmed by means of a nonlinear least-square fitting technique. Compared with previous models, the MTF estimate based on proposed model shows the lowest error in the presence of different noise. A practical application of MTF measurement in degraded image restoration also validates the accuracy of proposed method..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3454 (2010)
Image Coding Algorithm Using Optimal Scaling Scheme and Quadtree Partitioning
Zhang Libao, and Huang Ying
For improving the lossly image coding efficiency of integer wavelet transform (IWT) based on lifting scheme, the scaling factor is used in the lifting steps. However, the scaling factor is often an irrational number, which requires three additional lifting steps to assure the integer character of transform results. TheFor improving the lossly image coding efficiency of integer wavelet transform (IWT) based on lifting scheme, the scaling factor is used in the lifting steps. However, the scaling factor is often an irrational number, which requires three additional lifting steps to assure the integer character of transform results. They not only increase computational complexity of integer wavelet transform, but also raise the effect of rounding error on image compression. This paper presents a new image coding algorithm using optimal scaling scheme and quadtree partitioning. The new algorithm decomposes the image using integer wavelet without scaling factor and then only performs a multiplication on every subband with the new scaling factor, which reduces the computational complexity of the integer wavelet transform. During the image encoding, a new quadtree partitioning scheme is used to improve the searching efficiency of the significant coefficients. The experimental results show that the new coding algorithm has not only the well lossly compression efficiency, but also the lower computational complexity than the common IWT. This new method is valuable for future remote sensing and medical image compression..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3460 (2010)
Imaging Systems
3-Dimersional Reconstruction Based on Underwater Range Gated Images
Li Hailan, Wang Xia, Jin Weiqi, Bai Tingzhu, Huang Youwei, and Ding Kun
In order to conquer the depth of field limitation in underwater range-gated imaging, the advantages of laser radar imaging theory and images reconstruction are taken, considering the reality of our laboratory, range information acquisition process of underwater range gated serial images is analyzed in detail. In view oIn order to conquer the depth of field limitation in underwater range-gated imaging, the advantages of laser radar imaging theory and images reconstruction are taken, considering the reality of our laboratory, range information acquisition process of underwater range gated serial images is analyzed in detail. In view of the characteristics of range gated images obtained in different quality water, subtracting background image from object image, choosing maximum layer progressive reconstruction among adjacent images according to period plus tiny time offset and reconstruction after segmentation are used to images. Serial scene “slices” in different range is attained to testify the proposed algorithm. An image comprising objects in all “slices” from 8.2 to 13.2 m is reconstructed. In order to explain the range information in the reconstructed image, a pseudo color image is reconstructed by three adjacent images containing range information from 10.7 to 13.2 m..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3464 (2010)
Study of the Radiation Calibration of TDI-CCD Spatial Stereo Camera
Ren Huanhuan, Ruan Ping, He Jianwei, Xue Bin, Qiao Weidong, Liang Shitong, and Wang Hongwei
The principle of the radiation calibration of TDI-CCD spatial stereo camera is introduced in detail in three aspects of dark current data, relative calibration and absolute calibration. Then the process of the radiation calibration is briefly described. Finally the data measured during the calibration is disposed and aThe principle of the radiation calibration of TDI-CCD spatial stereo camera is introduced in detail in three aspects of dark current data, relative calibration and absolute calibration. Then the process of the radiation calibration is briefly described. Finally the data measured during the calibration is disposed and analyzed. How the dark current is eliminated effectively and the method of the relative calibration in each condition is mainly illustrated. In order to effectively eliminate the dark current, a part of the direct current, two methods are compared. In the process of relative calibration, the calibration matrices are calculated after analyzing a huge number of data. And in the tolerance of the system, the most suitable matrix to any condition is optimized among many matrices. It is proved that the average deviation of any calibrated image is usually between 0.08 and 1.5 in gray value, and the maximum error is 2.80%. So the complexity of the calibrating process is decreased in the practical application, and the image processing in the later stage of the work is also simplified..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3467 (2010)
Static Simulation Experiment of Image Motion Measurement Based on Optical Joint Transform Correlator
Yi Hongwei, Zhao Hui, Wen Desheng, and Li Yingcai
The optical joint transform correlator (JTC) is an effective technical way for image motion measurement of the space camera. Its basic principles are presented，and performance is evaluated through static simulation experiment. A calibrated image set is tested by the experimental device. The results show that, the measuThe optical joint transform correlator (JTC) is an effective technical way for image motion measurement of the space camera. Its basic principles are presented，and performance is evaluated through static simulation experiment. A calibrated image set is tested by the experimental device. The results show that, the measurement accuracy can be controlled below 0.2 pixel in two directions, which is satisfied for the space camera. The influence of centroiding window size on cross-correlation peaks locating is analyzed, based on which, intensity weighted centroiding (IWC) is proposed instead of the traditional centroiding method, by which not only the influence of centroiding window size on image motion measurement is reduced, but also the measurement accuracy is improved..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3471 (2010)
Operating Distance Model of Near-Infrared Range-Gated Imaging System Based on Minimum Resolvable Contrast
Li Li, Qiu Su, Jin Weiqi, Wang Jihui, and Huang Youwei
The range-gated imaging (RGI) technique based on near-infrared or short-wave infrared pulsed laser illumination can reduce the influence of backscatter effectively, so it can improve the operating distance of the optical imaging system in night and adverse environment. It is researched and brought forwards the operatinThe range-gated imaging (RGI) technique based on near-infrared or short-wave infrared pulsed laser illumination can reduce the influence of backscatter effectively, so it can improve the operating distance of the optical imaging system in night and adverse environment. It is researched and brought forwards the operating distance model and the forecasting method of the RGI system according to the needs of the design and analysis of near-infrared RGI system, that is according to the traditional continuous (passive) imaging model calculations or test the performance of RGI system, based on the minimum resolvable contrast (MRC), using an equivalent exposure time integration principle, imaging results of periodic pulsed laser are converted, and then the equivalent band patterns RGI system is used for predicting the role of different target distances. The forecasting results and the actual experimental results have good consistency which indicate that the method is effective. This method can be used to analyze the design and function in many kinds of near-infrared RGI system, and may also apply to forecast the operating distance in the short-wave infrared system..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3481 (2010)
Design Analysis of a Complementary Double-Mirror Catadioptric Omnidirectional Imaging System
Chen Lidong, Wang Wei, Zhang Maojun, and Chen Wang
To solve the problems of low and non-uniform resolution in catadioptric omnidirectional imaging, a novel omnidirectional sensor of complementary imaging structure is designed, by using two reflecting mirrors. Each spatial object has two imaging positions, respectively in the inner and the outer ring of captured omnidirTo solve the problems of low and non-uniform resolution in catadioptric omnidirectional imaging, a novel omnidirectional sensor of complementary imaging structure is designed, by using two reflecting mirrors. Each spatial object has two imaging positions, respectively in the inner and the outer ring of captured omnidirectional images. The uniformity of resolution distribution is obviously improved due to complementary double imaging, and higher spatial resolution is achieved by limiting the vertical field of vision in a narrow range for some specific applications, such as military remote surveillance. Computational methods of the shape parameters and sizes of two mirrors are described in detail, and the mapping relations between omnidirectional image plane and cylindrical panoramic space are accurately derived based on ray tracing. Experimental results show that remarkable complementarities exist between the inner and outer ring of omnidirectional images, and detailed analysis of resolution distribution is presented. Moreover, sub-pixel sampling displacement between two image positions provides essential preconditions and foundations for further research on super-resolution reconstruction of cylindrical panoramic space..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3487 (2010)
Power Spectra-Based Auto-Focusing Method for Airborne Optoelectronic Platform
Zhao Zhibin, and Liu Jinghong
In order to retrieve the defocus in the optical system of airborne camera caused by the changes of temperature, pressure and other environment parameters in high altitude, focus measure algorithm based on power spectra and auto-focus search strategy are represented. Firstly, it is introduced that the power spectra of iIn order to retrieve the defocus in the optical system of airborne camera caused by the changes of temperature, pressure and other environment parameters in high altitude, focus measure algorithm based on power spectra and auto-focus search strategy are represented. Firstly, it is introduced that the power spectra of images taken from different region has the characteristic of invariance. Two betterments over the power spectra sum (PSS) focus measure function are proposed based on the main attenuation of power spectra in the high frequency. Then, full search (FS) strategy using changed steps is proposed in order to reduce the focus error caused by noise from environment. The results show that the FS strategy can locate the optimal focus position accurately when using search step length of 1 mm. The focus error is 0.3 mm which fulfills the requirement of system. The PSS proposed algorithms can indicate the defocus state of images taken by airborne camera, and it can also improve the properfies of saturation region and sensitiveness of the focus measure curve respectively. Search steps shorter than focus-depth can guarantee the validity of the result..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3495 (2010)
Instrumentation, Measurement and Metrology
Self-Mixing Interference in Laser Diode and Frequency Shift of Laser
Hu Xianfeng
Light feedback of external cavity and movement of external cavity mirror in self-mixing interference affect laser frequency. Light fields out of front and rear facets on internal cavity, frequency shift of laser and frequency of self-mixing interference signal are introduced from a model of complex resonant cavity. FreLight feedback of external cavity and movement of external cavity mirror in self-mixing interference affect laser frequency. Light fields out of front and rear facets on internal cavity, frequency shift of laser and frequency of self-mixing interference signal are introduced from a model of complex resonant cavity. Frequency shift of laser and frequency spectra of self-mixing interference signal are observed in experiment. Frequency shift of laser is made up resonance frequency shift and movement frequency shift. At lower moving frequency of external cavity mirror, frequency shift of laser out of the front and rear facets are almost the same as resonance frequency shift. At higher moving frequency of external cavity mirror, frequency shift of laser out of the front and rear facets are different from each other. Frequency shift of laser out of the front facet may be dominated by movement frequency shift. Frequency of self-mixing interference signals at extremely weak feedback light is the same as Doppler frequency shift of feedback light. Frequency of self-mixing interference signal at weak feedback light vibrates sharply and its highest frequency is more than 1.6 times of Doppler frequency shift of feedback light..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3501 (2010)
Focal Plane Design of Chang′e-1 Satellite CCD Stereo-Camera and Laboratory Radiation Calibration
Song Zongxi, Zhao Baochang, Gao Wei, Yang Jianfeng, and Ruan Ping
The special focal plane design and radiation calibration of Chang′e-1 satellite CCD stereo-camera are discussed. A wide-angle, telecentric and orthoscopic optical lens coupled with an area array CCD is used as a sensor in Chang′e-1 satellite CCD stereo camera to complete the three-line array self-propelling-sweeping imThe special focal plane design and radiation calibration of Chang′e-1 satellite CCD stereo-camera are discussed. A wide-angle, telecentric and orthoscopic optical lens coupled with an area array CCD is used as a sensor in Chang′e-1 satellite CCD stereo camera to complete the three-line array self-propelling-sweeping imaging. But with the existence of shutter smear, the exposure time has some great differences between the foresight, vertical sight and back sight. It brings difficulties to the radiometric calibration. This paper presents a solution of setting up a three-slit mask in front of the CCD focal plane, which makes the three line exposure time almost the same and after the residuals in the laboratory calibration are further adjusted, good result is obtained. This paper also introduces other performances in the radiation calibration including the estimation of the shortest exposure time, the registration of the saturation radiance, the dark current noise test, the linearity of CCD pixel response and the uncertainties of relative calibration and absolute calibration..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3508 (2010)
Determining Plastic Strain Ratio of Sheet Metal Based on Stereo Vision
Ye Nan, and Zhang Liyan
A new technique for determining the plastic strain ratio of sheet metal is proposed. After off-line calibration of the two cameras, digital images of the process of sheet metal surface deformation were temporally taken by the cameras so that two sets of time-synchronization image serial were obtained, the 3D shapes of A new technique for determining the plastic strain ratio of sheet metal is proposed. After off-line calibration of the two cameras, digital images of the process of sheet metal surface deformation were temporally taken by the cameras so that two sets of time-synchronization image serial were obtained, the 3D shapes of sheet metal surfaces at different deformation time were reconstructed by using stereo vision and digital image correlation methods consequently. Local major and minor strains were then evaluated in terms of finite strain theory. By exploiting the approximate equality of local strains at the same moment during uniform plastic deformation, the major and minor strain were converted into the strains in length and width directions, from which r value can finally be determined. Under the experimental conditions prescribed in GB/T 5027-2007, r values of AA6016T4PD, 2A12-T4 2 and 2A12-O were determined, and the results demonstrated the proposed technique was accurate and rapid..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3515 (2010)
Non-Intrusive Precise Measuring Method of Large Complex Surface
Zhu Jigui, Guo Lei, Lin Jiarui, Zou Jian, and Ye Shenghua
A non-intrusive precise measuring method for complex surface in size of tens of meters whose normal vector varies greatly is presented. Global control points and measured points are set by means of optical projection. Orientation camera and orientation target fixed on measuring camera are used to solve estimation problA non-intrusive precise measuring method for complex surface in size of tens of meters whose normal vector varies greatly is presented. Global control points and measured points are set by means of optical projection. Orientation camera and orientation target fixed on measuring camera are used to solve estimation problem of measuring camera′s initial position and posture. Then the three-dimensional coordinates of measured points are retrieved based on ray bundle adjustment technique. It overcomes the limitation of existing methods that coding targets must be set on measured surface, so it can accomplish non-intrusive measurement. Experimental results show that the total root mean square (RMS) error is 0.07 mm, therefore, the principle of method is reasonable and can solve problems with high accuracy and efficiency..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3524 (2010)
Integrated Optics
Minimum Mode Spot Size in a Three-Layer Dielectric Optical Waveguide
Yu Ping, Jiang Xiaoqing, Yang Jianyi, and Wang Minghua
The minimum mode spot size of a three-layer dielectric optical waveguide was studied. Based on the mode-field solutions expression of Maxwell function, The influences of mode polarization, waveguide size, dielectric coefficient difference, wavelength and asymmetry on mode spot size, according to its specified definitioThe minimum mode spot size of a three-layer dielectric optical waveguide was studied. Based on the mode-field solutions expression of Maxwell function, The influences of mode polarization, waveguide size, dielectric coefficient difference, wavelength and asymmetry on mode spot size, according to its specified definition are investigated. The analysis and simulation results indicated that there existed a minimum mode spot size (MMSS) in a three-layer dielectric optical waveguide. As to the symmetric waveguide, the MMSS of TE mode is inversely proportional to the square root of dielectric coefficient difference. However the MMSS of TM mode is dependent on the specified dielectric coefficients of waveguide and larger than that of TE mode. Both of them are proportional to the wavelength of guided wave. As to the asymmetric waveguide, the shape of mode spot is also asymmetric. The MMSS has the same dependences on dielectric coefficient difference as symmetric one. Besides, it decreases at first and then increases with the increasing of waveguide symmetry factor..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3530 (2010)
Propagation Properties of a Surface Plasmonic Waveguide with a Double-Square-Shaped Air Core
[in Chinese], [in Chinese], and [in Chinese]
A kind of surface plasmonic waveguide (SPW) with a double-square-shaped air core was designed. The propagation properties of the fundamental mode supported by this SPW are analyzed using the finite-difference frequency-domain method. The result shows that the longitudinal energy flux density of the fundamental mode disA kind of surface plasmonic waveguide (SPW) with a double-square-shaped air core was designed. The propagation properties of the fundamental mode supported by this SPW are analyzed using the finite-difference frequency-domain method. The result shows that the longitudinal energy flux density of the fundamental mode distributes mainly in the central area of the double-square-shaped air core. Adjusting the sides of the two squares, the center to center distance of the two squares and the working wavelength, the field distribution range as well as the degree of the interaction of field with silver can be adjusted, then the effective index, propagation length and mode area of the fundamental mode can be adjusted. Compared with the SPW with a double-circle-shaped air core, it is found that the propagation properties of this kind of SPW are better than the latter within 730~800 nm working wavelength range. This double-square-shaped SPW can be applied to the field of photonic device integration and sensors..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3537 (2010)
Materials
Effects of Electrophoretic Nano-Ag on Field Emission Properties of CNT Cathode
Ye Yun, Guo Tailiang, Lin He, Li Weizhi, and Jiang Yadong
Ag-CNT (carbon nanotube) composite cathodes are prepared on elaborate metal electrodes by electrophoresis and screen printing. The effects and conductive mechanism of nano-Ag on field emission properties of CNT cathodes are investigated. The morphologic images of nano-Ag film and Ag-CNT composite cathode are observed bAg-CNT (carbon nanotube) composite cathodes are prepared on elaborate metal electrodes by electrophoresis and screen printing. The effects and conductive mechanism of nano-Ag on field emission properties of CNT cathodes are investigated. The morphologic images of nano-Ag film and Ag-CNT composite cathode are observed by scanning electronic microscopy (SEM). It is found that the nano-Ag particles are uniform and compact. The nano-Ag particles move to CNT cathode and fill up the contacting vacancy between CNT cathode and metal electrodes after co-sintered. So electronic transmission and heat transfer is improved between CNT cathode and metal electrodes. The experimental result show that the field emission properties, luminance and stability of CNT cathodes could be improved by the nano-Ag conductive film..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3542 (2010)
Preparation and Investigation on Down-Conversion Near Infrared Emission of Tb3+，Yb3+ Co-doped Y2O3 Transparent Ceramics
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Tb3+, Yb3+ codoped Y2O3 (mole fraction x=0.02, 0.05, 0.1) transparent ceramics of high transparency have been prepared by vacuum sintering and the down-conversion near infrared (NIR) emission has been demonstrated upon a 484 nm excitation. The dominant energy transfer mechanism is the cooperative down-conversion from 5Tb3+, Yb3+ codoped Y2O3 (mole fraction x=0.02, 0.05, 0.1) transparent ceramics of high transparency have been prepared by vacuum sintering and the down-conversion near infrared (NIR) emission has been demonstrated upon a 484 nm excitation. The dominant energy transfer mechanism is the cooperative down-conversion from 5D4 level of one Tb3+ ion to the 2F5/2 level of two Yb3+ ions. The suppression of Tb4+ during vacuum sintering and the suppression of Yb2+ due to the nature of Y2O3 lattice, together with the large energy gap between Tb3+5D4 level and Tb4+-Yb2+ charge transfer state (CTS) and the low phonon energy of Y2O3 make the non-radiative influence from the CTS negligible. In addition, the contribution of Tb3+5D4→one Yb3+2F5/2 (non-radiative)→Yb3+2F7/2 (radiative) process to NIR emission should be little due to the large energy gap between Tb3+5D4 level and low phonon energy of Y2O3..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3547 (2010)
Fabrication and Properties of Silica Photonic Crystal Heterostructures
Yan Hongwei, Zhang Lin, Zhu Fanghua, Li Bo, and Yin Qiang
Silica opal structures and photonic crystal heterostructures are fabricated by vertical deposition technique. The structures of samples are characterized by scanning electron microscopy and optical transmission spectra. The long-range order of the silica opals is confirmed by fast Fourier transform analysis of scanningSilica opal structures and photonic crystal heterostructures are fabricated by vertical deposition technique. The structures of samples are characterized by scanning electron microscopy and optical transmission spectra. The long-range order of the silica opals is confirmed by fast Fourier transform analysis of scanning electron microscopy image at different region of the same sample. The smooth decline of background in the transmission spectra of different silica opals is attributed to the contribution of scattering from the structural defects. The photonic stop band of photonic crystal heterostructures exhibits obvious broadening and flattening in contrast to the corresponding silica opals, where the effect of film thickness is considered. The positions of photonic stop band show consistency between photonic crystal heterostructures and corresponding silica opal structures. The overlap of photonic stop band in heterostructures is discussed in detail..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3592 (2010)
Medical Optics and Biotechnology
Application of Near Infrared Reflectance Spectroscopy-Radial Basis Function Neural Network for Non-DestructiveDetermination of Coriolus Versicolor
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A calibration model (NIRS-RBFNN) based on combination of near infrared reflectance spectroscopy and radial basis function neural network (RBFNN) has been proposed for synchronous and rapid non-destructive determination of Coriolus versicolor. Savitzky-Golay smoothing (SGS), fast Fourier transform (FFT), derivative of wA calibration model (NIRS-RBFNN) based on combination of near infrared reflectance spectroscopy and radial basis function neural network (RBFNN) has been proposed for synchronous and rapid non-destructive determination of Coriolus versicolor. Savitzky-Golay smoothing (SGS), fast Fourier transform (FFT), derivative of wavelet transformation (WT) and wavelet packet transformation (WPT) with multi-scale analysis were used to dispose the original NIRS, then principal component analysis (PCA) method is used to obtain the principal components (PC) scores. The anterior 15 PC scores were used as input data. These developed RBFNN have been optimized by selecting suitable parameters of input data, numbers of hidden layer neurons and spread constant through different pretreated spectra of calibration. The optimal quantitative analysis (NIRS-RBFNN) model for polysaccharide and protein of coriolus versicolor: for polysaccharide the optimal model is 6 scales reconstructed spectra of WPT, model parameter is WPT-NIRS-RBFNN(7-12-1, 3.2)，and root mean squared error of cross validation(RMSECV) is 0.009897, Rcv=0.98357; root mean squared error of predictions(RMSEP) is 0.00909; Rp=0.98283. For Protein the optimal model is 6 scales reconstructed spectra of WPT, model parameter is WPT-NIRS-RBFNN(12-10-1, 3.0)，and RMSECV is 0.00524, Rcv=0.99426; RMSEP is 0.00998; Rp=0.98246. These results show that the model has good robustness and precision and NIRS technology is convenient, rapid, no pretreatment and no pollution that this method could be popularized in the in situ measurement and the on-line quality control for coriolus versicolor..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3552 (2010)
Cavitation Effect of Pulsed Holmium Laser and Dynamic Characteristics of Hard Tissue Ablation Underwater
Lü Tao, Xiao Qing, and Li Zhengjia
Dynamic characteristics of cavitation bubbles and hard tissue ablation induced by fiber-guided free-running holmium laser pulses are recorded by high-speed photography. At the same time, a needle hydrophone is used to measure shock wave signals which are emitted upon cavitation bubble collapse. Experimental results shoDynamic characteristics of cavitation bubbles and hard tissue ablation induced by fiber-guided free-running holmium laser pulses are recorded by high-speed photography. At the same time, a needle hydrophone is used to measure shock wave signals which are emitted upon cavitation bubble collapse. Experimental results show that more than four oscillation periods of 368, 144, 56 and 40 μs, respectively, are achieved. During the oscillation process, most energy focuses on the first period and the cavitation bubble becomes more and more irregular in shape. The intensity of the four shock waves reaches 20.5×105, 12.6×105, 5.1×105 and 2.0×105 Pa, as cavitation bubble collapse, respectively. The water layer on hard tissue surface can not only enhance ablation efficiency, but also improve lubricity of ablation craters..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3558 (2010)
Application of Microscopic Interferometry for Quantitative Phase Measurement of Red Blood Cells
Xue Liang, Lai Jiancheng, Wang Shouyu, and Li Zhenhua
In order to improve detection speed and accuracy of biological cells, microscopic interferometry which is a noncontact technique for imaging of phase objects is proposed, i.e., red blood cells. The technique combines the principles of off-axis interferometry, confocal microscopy and high-speed image-capture technology In order to improve detection speed and accuracy of biological cells, microscopic interferometry which is a noncontact technique for imaging of phase objects is proposed, i.e., red blood cells. The technique combines the principles of off-axis interferometry, confocal microscopy and high-speed image-capture technology and is characterized by optimized spatial resolution and real-time acquisition capabilities. Single carrier-frequency interferogram is captured from experimental setup. According to fast Fourier transform phase retrieval method and path-unfollowing unwrapping algorithm, the quantitative phase distributions of red blood cell are gained and agree well with the previous optical phase models. Analysis shows that the resolution of introduced system reaches sub-micron dimension. It provides a breakthrough method for real-time observing and quantitative analyzing of cells in vivo..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3563 (2010)
Optical Design and Fabrication
Study on Sensitivities of Ghost Images to Lens Fabrication Errors in High Power Laser Facilities
Zhang Yan, Zhang Yanli, Li Xiaoyan, Sun Pingping, and Zhu Jianqiang
As the further discussion on the ghost images in high-power laser facilities, the sensitivities of the ghost images focal positions to lens fabrication errors are analyzed based on the traditional studies. The general expression of ghost images focal length is deduced approximately, and the relation between shifts of gAs the further discussion on the ghost images in high-power laser facilities, the sensitivities of the ghost images focal positions to lens fabrication errors are analyzed based on the traditional studies. The general expression of ghost images focal length is deduced approximately, and the relation between shifts of ghost images focal position and errors of lens parameters are calculated based on the matrix optics. The numerical calculation results by taking the focal lens of the final optical assembly in SG-Ⅱ upgraded system as example indicate that the ghost images are sensitive to the lens central errors, but insensitive to the errors of curvature radius and center thickness. It can offer the reference in optical designs..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3568 (2010)
OPTOELECTRONICS
Study on Under-Gate Field Emission Display with Electron Beams Self-Focus Effect
Wu Chaoxing, Zhang Yongai, Zhang Jie, Li Yu, and Guo Tailiang
An under-gate field emission display (FED) with a concave cathode is proposed. Ansys software is used to simulate the electric field distribution and the focus effect of electron beams. The curvature radius of a concave cathode which affects the self-focus is investigated. The results demonstrate that the concave cathoAn under-gate field emission display (FED) with a concave cathode is proposed. Ansys software is used to simulate the electric field distribution and the focus effect of electron beams. The curvature radius of a concave cathode which affects the self-focus is investigated. The results demonstrate that the concave cathode focuses electron beams which emit from cathode obviously. As the curvature radius of a concave cathode decreases, the focus effect is enhanced and the radius of spots on the anode decreases too. A 10 cm×10 cm FED with a good self-focus effect is successfully prepared using screen printing. The field emission image shows that the structure can decrease the size of spots and improve the resolution. The anode current is well modulated by a gate voltage of 100～250 V under an applied anode voltage of 600 V..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3574 (2010)
Ab-initio Investigation of Anisotropic Optical Properties of Sr2RuO4
Cai Jianqiu, Tao Xiangming, Luo Haijun, Jin Qingli, and Huang Yunmi
The anisotropic optical properties for superconductor Sr2RuO4 have been studied by full-potential linearized augmented plane wave (FLAPW) method based on density functional theory. In order to simulate the temperature effects, Lorentzian broadening (set as δ=0.20 eV) is added into optical matrix elements during the calThe anisotropic optical properties for superconductor Sr2RuO4 have been studied by full-potential linearized augmented plane wave (FLAPW) method based on density functional theory. In order to simulate the temperature effects, Lorentzian broadening (set as δ=0.20 eV) is added into optical matrix elements during the calculation in these spectra. The spectra of reflectivity R(ω), optical conductivity σ(ω) and electron energy loss have been calculated. These results consist quite well with experiments as a whole. And the optical conductivity spectrum along x-axis displays quite different features in comparison with that of z-axis. Along x-axis, σ(ω) spectrum shows an obvious Drude-like feature in low energy region while not along z-axis. The conversion between intra-band absorption and inter-band absorption appears at about 1.84 eV in the σ(ω) spectrum along x-axis. By further analysis, the anisotropy of optical properties should mainly arise from different band structure along two axes..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3580 (2010)
Photoelectric Properties of Alternating-Current Light-Emitting Diodes
Chen Yingliang, Lu Yijun, Gao Yulin, Lin Yue, Chen Huanting, Lei Ruirui, Guo Ziquan, Chen Guolong, and Chen Zhong
The optical and electrical parameters of AC-LEDs driven by AC and DC source were tested at different alternating-current voltage, frequency and heat-sink temperature respectively. It is found that the values of luminous flux, optical power and luminous efficacy of device driven by DC source are larger than those by AC-The optical and electrical parameters of AC-LEDs driven by AC and DC source were tested at different alternating-current voltage, frequency and heat-sink temperature respectively. It is found that the values of luminous flux, optical power and luminous efficacy of device driven by DC source are larger than those by AC-source in the same active power. Because of thermal effects, efficiency droop and equivalent series resistances, the luminous efficacy of AC-LEDs firstly increases and then decreases with the active power increases. By changing the temperature of heat sink, the infcuence of temperatures on peak wavelength, optical power and luminous efficacy of AC-LEDs were further discussed..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3586 (2010)
Physical Optics
Study of Focal Spot of Radially Polarized Beam
Yan Jie, Lu Yonghua, Wang Pei, and Ming Hai
The first order radially polarized beam is with cylindrical symmetry in polarization. It is commonly thought that radial polarization leads to the best light beam focusing in terms of spot size, and the focal spot has strong longitudinal field. Using numerical calculation method, it is presented that the focal spot of The first order radially polarized beam is with cylindrical symmetry in polarization. It is commonly thought that radial polarization leads to the best light beam focusing in terms of spot size, and the focal spot has strong longitudinal field. Using numerical calculation method, it is presented that the focal spot of radially polarized beam which is smaller than the size along polarization direction of focal spot with linear polarized beam can be obtained, if the angle between refracted light and optical axis is larger than 70°. But the size perpendicular to polarization direction of focal spot with linear polarized beam is always smaller than that of radially polarized beam. In addition, it can lead to the smaller focal spot of radially polarized beam when an annular aperture diaphragm is inserted in optical path. But this method is not suitable for the situation of linearly polarized beam along polarization direction..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3597 (2010)
Quantum Optics
A Study on the Pairwise Concurrence Entanglement in the Multipartite Open System
Sun Chao, Zhang Yingjie, Meng Xiangshui, and Xia Yunjie
The entanglement dynamics of the multipartite open system is investigated, which is arranged in such a way that two atoms are coupled to a common non-Markovian reservoir and another two atoms are embedded in the other remote non-Markovian reservoir. The results show that the initial entanglement of two atoms can transfThe entanglement dynamics of the multipartite open system is investigated, which is arranged in such a way that two atoms are coupled to a common non-Markovian reservoir and another two atoms are embedded in the other remote non-Markovian reservoir. The results show that the initial entanglement of two atoms can transfer to another two separated atoms, the two reservoirs have an intermediate effects in the transfer process. Through studying the pairwise concurrence entanglement in the multipartite open system, it is also found that the initial entanglement can cause the phenomenon of entanglement sudden death under certain condition, and the simultaneous entanglement sudden birth would appear in another separated atoms and the two reservoirs..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3604 (2010)
Quantum Coherence Properties in Lambda Three-Level System Driven by Two Coupling Fields
Yang Lijun, Zhao Min, Feng Xiaomin, Li Xiaoli, and Zhang Lianshui
Quantum coherence of a Λ-three-level scheme driven by two coupling fields is investigated. By sloving density matrix motion equations under dipole approximation and rotating wave approximation, numerical results are obtained. It is shown that the probe absorption spectrum has amplification as well as absorption when boQuantum coherence of a Λ-three-level scheme driven by two coupling fields is investigated. By sloving density matrix motion equations under dipole approximation and rotating wave approximation, numerical results are obtained. It is shown that the probe absorption spectrum has amplification as well as absorption when both coupling fields are resonant with corresponding resonant transitions, and it exhibits the superposition of double electromeqnetic induced absorption (EIA) and Mollow profile. The dependence of the position and intensity of the double EIA and Mollow profile on Rabi frequency of two coupling fields is investigated.The results can be accounted for dressed-state formalism. Therefore, EIA and Mollow frequency tuning can be performed by changing the intensity of the coupling fields..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3610 (2010)
Electromagnetically Induced Absorption and Transparency of Four-Level System Driven by Radio-Frequency Field in Eu3+Y2SiO5 Crystal
Fu Zhenxing, and Liu Birui
A four-level system in Eu3+Y2SiO5 crystal is obtained through coupling a hyperfine level with a radio-frequency field. The absorption properties of this four-level system driven by a radio-frequency field are investigated by means of density matrix equation of motion. It is shown that the two contrary quantum effects, A four-level system in Eu3+Y2SiO5 crystal is obtained through coupling a hyperfine level with a radio-frequency field. The absorption properties of this four-level system driven by a radio-frequency field are investigated by means of density matrix equation of motion. It is shown that the two contrary quantum effects, electromagneticically induced transparency (EIT) and electromagnetically induced absorption (EIA) can be obtained in the absorption spectrum of the system due to the interaction of both optical coupling and radio-frequency fields. When radio-frequency field resonates with corresponding levels, EIT effect presents within two-peak area of Autler-Townes splitting caused by radio-frequency field. But nonresonant radio-frequency field can cause EIA. The positions of EIT and EIA are determined by the detuning of optical coupling field. The linewidth, position and conversion of EIT and EIA can be controlled by changing detuning, Rabi frequency of optical coupling and radio-frequency fields..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3615 (2010)
Spectroscopy
Panax Quinquefolium′s Active Ingredients Detecting Method Based on LCTF Spectrograph
Li Zilei, Wang Lin, Pang Qichang, Ma Ji, Zhao Jing, and Lin Fubin
A liquid crystal spectrograph is designed to collect Panax quinguefolium′s spectral image based on liquid crystal tunable filter（LCTF）spectroscope. Panax quinquefolium slice is put under UV light, and its fluorescence image is collecteel by the instrument continuously. Panax quinguefolium′s fluorescence effect is obvioA liquid crystal spectrograph is designed to collect Panax quinguefolium′s spectral image based on liquid crystal tunable filter（LCTF）spectroscope. Panax quinquefolium slice is put under UV light, and its fluorescence image is collecteel by the instrument continuously. Panax quinguefolium′s fluorescence effect is obvious during the detection. Corresponding relations are found between fluorescence intensity and saponins which is panax quinquefolium′s effective active ingredient, when the slice of different grades and standards is detected. So a simple, fast, non-destructive method, which can be applied to assess panax quinquefolium′s quality and ingredient, is established. More over, the slice′s fluorescence curve of spectrum and panax quinquefolium′s saponins 3 dimensional distribution spectrum can be obtained, its saponins′s distribution information can also be obtained..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3622 (2010)
Growth and Spectroscopic Properties of Tm3+Sr3La2(BO3)4 Crystal
Zhou Haifang, and Wang Guofu
The growth and spectroscopic properties of Tm3+Sr3La2(BO3)4 crystal are reported. Based on Judd-Ofelt theory, the intensity parameters are calculated to be Ω2=4.46×10-20 cm2, Ω4=3.18×10-20 cm2, and Ω6=1.88×10-20 cm2 according to the absorption spectrum. The emission cross section for the 3F4→3H6 transitiThe growth and spectroscopic properties of Tm3+Sr3La2(BO3)4 crystal are reported. Based on Judd-Ofelt theory, the intensity parameters are calculated to be Ω2=4.46×10-20 cm2, Ω4=3.18×10-20 cm2, and Ω6=1.88×10-20 cm2 according to the absorption spectrum. The emission cross section for the 3F4→3H6 transition are estimated to be 0.694×10-20 cm2 at 1.82 μm by the reciprocity method according to the absorption cross section, and the relation between gain cross section and the population inversion rate for the 3F4→3H6 transition is discussed. Compared with the other Tm3+-doped materials, Sr3La2(BO3)4 crystal has a larger emission cross section and wider tuning range. Therefore, Sr3La2(BO3)4 crystal may be a potential tunable near-infrared laser crystal..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3627 (2010)
Pure Spectral Analysis and Fluorescent Signal Separation for Multispectral Fluorescence Imaging
Huang Yuancheng, Zhang Liangpei, Li Pingxiang, and Zhong Yanfei
One of the most important issues in biomedical research is in vivo fluorescence-based multispectral imaging, but quantitative image analysis has been generally perturbed by the cross talk problem of fluorescence signals and significant autofluorescence problem of tissues. Spectral unmixing is a useful technique in multOne of the most important issues in biomedical research is in vivo fluorescence-based multispectral imaging, but quantitative image analysis has been generally perturbed by the cross talk problem of fluorescence signals and significant autofluorescence problem of tissues. Spectral unmixing is a useful technique in multispectral fluorescence imaging for reducing the effects of native tissue autofluorescence and separating multiple fluorescence probes in vivio. While spectral unmixing methods are well established in fluorescence microscopy, which typically rely on precharacterized spectra for each fluorophore. A spectral unmixing algorithm tailored for in vivo optical imaging that is able to find the signal distribution and the pure spectrum of each component is introduced. It is derived from multivariate curve resolution-alternative least square (MCR-ALS) method using multiple constraints such as nonnegative, equality, closure, unimodal, spectral range and normalization. The signal distribution maps help to separate autofluorescence from other probes in the raw images and hence provide better quantification and localization for each probe. The test of mixed spectral samples with abundance fractions generated by Dirichlet distribution demonstrates that the algorithm is robust with different noises and pure spectral. And a quantum dots mouse multispectral fluorescence image has convinced this method..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3631 (2010)
New Near Infrared Wavelength Selection Algorithm Based on Monte-Carlo Method
Hong Mingjian, Wen Quan, and Wen Zhiyu
Based on the feature of the (NIR) spectra, this paper analyses the method of wavelength selection using the partial least squaresc (PLS) regression coefficients and points out the existing problems, then proposes a new method for selecting wavelengths. It normalizes the PLS regression coefficients into the probability Based on the feature of the (NIR) spectra, this paper analyses the method of wavelength selection using the partial least squaresc (PLS) regression coefficients and points out the existing problems, then proposes a new method for selecting wavelengths. It normalizes the PLS regression coefficients into the probability of the selected corresponding wavelengths, then a Monte-Carlo simulation based on the aforementioned probability is calculated. Some PLS models are constructed and evaluated using different random wavelengths combinations. The model with minimum predictive error is retained and the corresponding wavelength combinations are selected. This procedure can be iterated using the previous selected wavelengths to select fewer and fewer wavelengths. This method is tested on 3 NIR datasets and compared with the PLS-based uninformative variable elimination (UVE-PLS) and genetic algorithm (GA). Experimental results show that this method could select fewer wavelengths without sacrificing the complexity and predictive ability of the PLS model and could effectively improve the accuracy and stability of the wavelength selection..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3637 (2010)
Measurement of Nitrate Radical in the Atmosphere by Direct Moonlight Passive Differential Optical Absorption Spectroscopy
Shi Peng, Xie Pinhua, Li Ang, Jiang Yu, Wu Fengcheng, and Qin Min
Nitrate radical plays (NO3) an important role in the nighttime atmosphere. By using direct moonlight as light source, a passive differential optical absorption spetroscopy (DOAS) system with automatic star-finder system and CCD spectrometer, is developed to measure the nighttime NO3 vertical column abundance of NO3. WaNitrate radical plays (NO3) an important role in the nighttime atmosphere. By using direct moonlight as light source, a passive differential optical absorption spetroscopy (DOAS) system with automatic star-finder system and CCD spectrometer, is developed to measure the nighttime NO3 vertical column abundance of NO3. Water vapor cross section is calculated using a line-by-line approach with considering the dependence of cross section on the temperature and water vapor amounts. By using air mass factor(AMF), the vertical column density (VCD) of NO3 radical is converted from slant column density (SCD). The max value of SCD is under 1.7×1014 molecule/cm2. As the sun rises, the observed column abundance decreases rapidly..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3643 (2010)
Spectral Fine Structure and Jahn-Teller Effect of LiNbO3Ni2+ Crystals
Jiao Yang, Yin Chunhao, Bai Qiufei, and Liang Ning
Applying crystal field theory and irreducible representation method, the completely diagonalized Hamiltonian matrices of 3d8 ion configurations in the trigonal symmetry sites have been established, which include four kinds of microscopic magnetic interactions: spin-orbit interaction, spin-spin interaction, spin-other-oApplying crystal field theory and irreducible representation method, the completely diagonalized Hamiltonian matrices of 3d8 ion configurations in the trigonal symmetry sites have been established, which include four kinds of microscopic magnetic interactions: spin-orbit interaction, spin-spin interaction, spin-other-orbit interaction and orbit-orbit interaction. Based on the matries, spectral fine structure and zero-field splitting parameters of LiNbO3Ni2+ crystall are calculated. Jahn-Teller effect, and effects of four microscopic magnetic interoctions on crystal spectral and zero-field splitting parameter are investigated. The results show that Jahn-Teller effect exists in this crystal and spin-orbit interaction makes uppermost contribution to energy level and zero-field splitting parameters while calculated values will be closer to the experimental values when the other three interactions are taken into account..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3649 (2010)
Detection of Water Vapour Based on Integrated Cavity Output Spectroscopy
Pei Shixin, Cui Fenping, Zhang Chengyi, and Li Chuanqi
A system of integrated cavity output spectroscopy (ICOS) based on a tunable distributed feedback (DFB) diode laser (TDL) is described. In this system a tunable DFB diode laser with the central output wavelength 1315 nm is used as the light source, the length of the absorption cell is 38 cm which is consisted by two mirA system of integrated cavity output spectroscopy (ICOS) based on a tunable distributed feedback (DFB) diode laser (TDL) is described. In this system a tunable DFB diode laser with the central output wavelength 1315 nm is used as the light source, the length of the absorption cell is 38 cm which is consisted by two mirrors with high reflectivity, near the laser central wavelength 1315 nm, the mirror′s reflectivity is about 99.7%. Presentation of experimental principle, experimental scheme and diode laser wavelength calibration are given; As experimental result, the absorption spectrum of water vapour at 7612.026, 7612.269 and 7610.224 cm-1 are obtained and a detection sensitivity of 2.02×10-7 cm-1 has been achieved. It is experimentally demonstrated that ICOS is a high sensitive and high resolution spectral technology with the advantage of simple experimental setup and easy operation..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3655 (2010)
Thin Films
Simulated Annealing Algorithm for Multi-Layer Optical Thin Films
Zhang Xiaojuan, Qiao Guanjun, and Liu Hanchen
The evaluation function of multi-layer optical thin film systems is a complex nonlinear multi-modal function. Traditional numerical methods could hardly obtain global extreme when the properties of evaluation function are unknown, with calculation of instability and low efficiency. Simulated annealing algorithm (SAA) eThe evaluation function of multi-layer optical thin film systems is a complex nonlinear multi-modal function. Traditional numerical methods could hardly obtain global extreme when the properties of evaluation function are unknown, with calculation of instability and low efficiency. Simulated annealing algorithm (SAA) exhibites some advantages such as high efficiency, less restricted by the initial solution and ability of obtaining global extreme. This is because SAA acceptes the optimized solution and part of the poor solution at the same time. General simulated annealing algorithm is improved by adding heating and memory module. Improved algorithm could select the initial value of control parameters more reasonably and memorize the optimal solution ever encountered in search process. Thus the ability to jump out of local optimum “trap” is improved accordingly. Antireflective film, neutral spectroscope and 10.4 μm long-wave pass filter desiged by improved algorithm, the value of evaluation function is decreased by 77.6%, 31.9%, 96.2% respectively. Film system has good spectral characteristic and more flat transmittance curves..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 30, Issue 12, 3660 (2010)
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